Hi @bazzbomb Sorry you cannot watch BT Sport on the Sky Q mini. I've moved your post as the previous thread was already resolved.
You'll find that the SkyQ Mini box doesn't have a viewing card slot. This means you can't get BT Sport just for your SkyQ Mini. You'll need to have it on your main SkyQ Box before you add a BT Sport Second Box subscription for your SkyQ Mini. An Extra Box subscription costs £5 per month.
Post back and let me know if you want to add the Extra Box subscription.